A stop and wait mode is generally used in hybrid automatic repeat request (Hybrid Automatic Repeat Request, HARQ for short hereinafter), that is, every time a transmit end sends a data packet, the transmit end temporarily stops and waits for acknowledgement information from a receive end. When the data packet reaches the receive end, the receive end performs error detection on the data packet, and if the received data packet is correct, returns an acknowledgement (Acknowledgment, ACK for short hereinafter) signal, or if the received data packet is incorrect, returns a negative acknowledgement (Negative Acknowledgement, NACK for short hereinafter) signal. When receiving the ACK signal, the transmit end sends new data, or otherwise resends the previously transmitted data packet. Therefore, an HARQ process is a process from data transmission to an ACK feedback or a NACK feedback of data. A Long Term Evolution (Long Term Evolution, LTE for short hereinafter) system uses a stop and wait protocol of eight processes, that is, the transmit end concurrently runs eight different stop and wait processes on a channel, and the data transmit end sends a data block of another HARQ process to the data receive end before receiving a feedback message of a previous HARQ process. In addition, a time sequence relationship between a sending moment when the data transmit end sends one piece of HARQ process data and a moment when the data transmit end receives an HARQ-ACK feedback of the process data is preset. That is, after receiving an HARQ-ACK feedback of one HARQ process, the data transmit end may determine, according to a preset time sequence relationship between a transmission moment of the process data and a receiving moment of the HARQ-ACK feedback, an HARQ process for which the HARQ-ACK feedback is provided.
To obtain larger transmission bandwidth, a carrier aggregation technology is introduced into the LTE system. For carrier aggregation between base stations, because data scheduling of multiple downlink carriers that belong to different base stations is independently performed due to non ideal reverberation (Non Ideal Reverberation) between the base stations, when working in a carrier aggregation system between the base stations, user equipment (User Equipment, UE for short hereinafter) needs to separately send an HARQ-ACK feedback for downlink data transmission of multiple base stations and cannot use a manner in which HARQ-ACK feedbacks of the multiple base stations are sent to one base station in a case of ideal reverberation (Ideal Reverberation). However, there may be a type of UE of a low capability, where uplink sending of the type of UE cannot be operated on carriers corresponding to multiple evolved NodeBs (evolved NodeB, eNB for short hereinafter) at the same time, and can only be operated on an uplink carrier corresponding to one eNB at every moment. When working in a CA system between the foregoing eNBs, the type of UE can only use a time division manner to transmit uplink data to the multiple base stations, so that the multiple base stations all learn an HARQ-ACK feedback status of their respective downlink data transmission.
However, because a time sequence relationship between a sending moment when a data transmit end sends one piece of HARQ process data and a moment when the data transmit end receives an HARQ-ACK feedback of the process data is preset, to comply with the preset time sequence relationship, a data receive end feeds back an HARQ-ACK to multiple base stations in the time division manner, so that scheduling of downlink carriers by the base stations at a moment also satisfies a corresponding time division manner. Therefore, a frequency spectrum resource of a carrier aggregation system cannot be fully used, which leads to a limited peak transmission rate of a user.